In the field of network communications, network elements, for example routers, are provided to create communications links between routers separated by a physical distance, such as between domains. The network elements also have to be replaced from time-to-time.
In order to assist configuration of such network elements after physical installation, automatic configuration techniques have been implemented in the network elements to simplify configuration of the network elements. For example, Ethernet routers, operating in accordance with the Institute of Electrical and Electronic Engineers (EEEI) 802.3 standard, are able to perform a so-called auto-negotiation process.
Consequently, in respect of an optical Gigabit Ethernet link established between a pair of Gigabit Ethernet capable hosts that both support auto-negotiation, respective Physical Conversion Sub-layers (PCSs) of the two hosts use the link to establish their respective operational credentials after power-up and before normal communication is performed by the hosts. In this respect, special reserved code words are used by each PCS to indicate to each other the contents of various respective registers, thereby providing each other with information concerning their respective capabilities. In effect, each PCS advertises to its counterpart its respective capabilities. The register used is known as an “Advertisement register”, contents of the “Advertisement register” that a first Ethernet host receives from a second Ethernet host, at an opposite end of the communications link, are placed into a similarly sized local register by the first Ethernet host, known as a “Link Partner Ability” register”.
During expected operation, each host compares the contents of the locally stored Advertisement register with the Link Partner Ability register, and by following a set of simple rules, each PCS determines a common mode of operation achievable by both PCSs. A resolved set of operational characteristics is then sent back by each PCS to the other so that each PCS can “see” what the opposing end has determined as the common mode of operation. If both PCSs arrive at the same common mode of operation, and after a brief pause, the first and second Ethernet PCSs then offer their services to their respective higher protocol stack layers based upon the agreed common mode of operation, and normal communication then takes place between the first and second Ethernet hosts. On the other hand, if the common mode of operation cannot be agreed, the PCSs revert to exchanging the Advertisement registers again, implying a disagreement between the first and second Ethernet PCSs as to the proposed common mode of operation and a desire to re-start the auto-negotiation process.
However, since its inception, the auto-negotiation process used on Gigabit Ethernet links has proved problematic: problems have been found in various optical products produced by various vendors. System administrators have therefore been known to disable the auto-negotiation feature of networking devices when installing the devices, preferring manual configuration, which while taking more time and effort to configure, usually works more reliably. The benefits of having the auto-negotiation feature for gigabit Ethernet capable equipment are therefore lost. Consequently, if one of the networking devices in the communications link is replaced, a new unit has to be configured manually with exactly the same configuration of its counterpart device at the other end of the link. Whilst configuration parameters for optical Gigabit Ethernet are not too numerous, mistakes can still be made when configuring devices, leading to a link that does not operate correctly.
In order to facilitate the auto-negotiation process a so-called “Internet Advisor” unit having a so-called Gigabit Ethernet “Under-cradle” module is available from Agilent Technologies, Inc. and can be installed in the communications link. The Internet Advisor unit is primarily a Protocol analyser for capturing, displaying, and analysing messages that flow over the communications link. However, the Internet Advisor also has a secondary mode for capturing auto-negotiation messages that take place on a Gigabit Ethernet system link, allowing the systems administrator to diagnose any problems that can prevent normal communication taking place between nodes using the communication link.
Whilst useful as a protocol analyser, the Internet Advisor is bulky and requires a dedicated AC power supply, and a site to locate it during operation; space to site the Internet Advisor is not always easy to find in an already full equipment room containing many racks and closets of networking equipment. Additionally, it is necessary to re-route original optical fibres to connect the Internet Advisor unit into the communications link and a new pair of optical fibres also needs to be connected to provide the Internet Advisor with optical signals. Once any problem has been diagnosed and the communications link has been established and running, the Internet Advisor unit then has to be disconnected, the original optical fibre cabling re-established, and auto-negotiation has to take place once more.